Treatment of metals



G. H. HOWE TREATMENT OF METALS June 12, 1928.

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UNITED STATES 1,673,624 PATET OFFICE.

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BREATHE-NT Application filed January 2, 1225. Serial Ho. 63.

My invention relates to the treatment of metals to prevent oxidation such as will ordinarily occur at high temperatures, and has for its object a continuous process of I treating metals for this purpose.

More specifically, my invention relates to the protection of metals, such as iron or copper, from oxidation and high temperatures, by means of a surface coating of anll) other metal, such as aluminum, which forms a surface alloy with the metal to be pro- In accordance with one method the aluminum is applied in powdered form at high temperatures, Where the metal to be 1% protected is in the form of a long; wire or red, however, it would be advantageous to apply the aluminum by passing thewire or rod continuously through a bath of molten aluminum, With this method, however, the

so in the molten aluminum tends to collect at the Quint where the wire emerges from the but and cling to the wire, forming lumps at in carrying out my invention, 1 ass the so wire continuously through a bath molten aluminum and heat the surface of the bath at the int where the wire emerges there-v from w erebv do its of dress on the wire are preven have also provided bellies 30 whereby deposits of aluminum are further prevented and the molten aluminum caused to circulate.

For a more complete understanding of my invention, reference-should be had to the u accompan g drawing in which Fig. 1 is a view m y in section showing the treatment of a wire in accordance with my invention; Fig. 2 is a diagrammatical'view showing the surface of the bath as the wire 3 and 4 are ahowingdetails of the apparatus of ficferring to the drawing, in carrying out my invention I provide a suitable crucible which is a molten bath 11 of the treating metal, for example, aluminum. As shown, the crucible can conveniently be placed in a suitable electric furnace 12 provided with a resistance-heatingconductor whereby the aluminum is maintained inv a molten state throughout the treating p The wire 14 which is tobe a coating oi another treating metal is preferably first coated with a suitable metal which alloys readily with both. the foundation metal of the wire and the treating metal. Metals suitable for this intermediate alloying metal are Zinc, tin and nickel. When aluminum is the treating metal and the wire is made of iron, tin is preferably used as the intermediate alloying metal, and when a copper Wire is to be treated nickel is preferably used as the intermediate alloying metal. This intermediate alloying metal may be applied in any well known manner.

As shown, the wire 14, having first been given a coating of a suitable intermediate alloying motel, is fed from a spool 15 downward into the bath oi molten aluminum, around a guide 16, and then upward out of the bath and thence over a gulde pulley 17 to a suitable spool, not shown, on which the treated wire is wound. A suitable bracket 18 is provided which extends downward into the molten aluminum and forms a support {or the guide lfi. The guide 16 is provided with flanges 16.

As is well known, molten aluminum oxidizes very rapidly and the oxide of aluminum has substantially the same gravity as the pure aluminum It therefore is mixed with the pure aluminum throughout the bath. As the wire is drawn through the aluminum, the dross, consisting of the oxide of aluminum and other impurities, is drawn along with the wire and tends to collect at the surface. The accumulation of this dross at the surface forms a rising meniscus about the wire, as indicated at 19, Fig. 2. This meniscus gradually builds up and cools until finally a portion of dross adheres to-the wire and is drawn ed with it. This results in lumps of dross at intervals on the wire.

In accordance with my invention, I pre-' vent the formation of these lumps of dross ,on the wire by suitably heating the surface of the molten aluminum bath at the point where the wit emerges. For example, provide a hydrogen burner secured on a suitable bracket 21.: This burner is adjusted so as to roject its flame 22 on the accumulation of dross formed around the wireas it emerges from the bath. The efiect of the'heat from the flame 22 is to break down the accumulation of dross and prevent its adhering to the wire. This action of the flame on the rising meniscus is indicated at 23, Fig. 2. Furthermore, the blowing action of the current of hot gases of the flame has an appreciable effect in dissipating the accumulation of dross. The dross is broken down by the heat into a powdered form and there is a tendency for this powder to be blown to one side by the flame.

I have also provided baffles 24 and 25 which are submerged in the molten aluminum and secured to the bracket 18 at suitable intervals. These baflles are horizontally disposed and are provided with slots 26 and 27 through which the wire passes in its journey upward out of the molten aluminum. These baflles. present substantially horizontal flat reflecting surfaces on their lower sides. Their action is to deflect the dross in the molten aluminum, which is drawn along by friction with the rapidly moving wire, and thereby prevent the dross from being drawn to the surface to some extent, and also to set up a circulation of molten aluminum in the crucible whereby the hottest molten aluminum is brought into contactwith the wire.

With this method, the coating of aluminum has been successfully applied with the wire passing through the bath at the rate of 40 to 60 feet per minute. The aluminum may not alloy with the metal of the wire to any considerable extent when it is applied since it will alloy mainly with the intermediate coating of tin or other metal on the wire. Upon the subsequent application of heat when the wire it put in use however, the aluminum penetrates the foundation metal of the wire and alloys therewith, thus forming a heat resisting surface coating.

While I have described my invention as embodied in concrete form and as operating in a specific manner in accordance with the rovisions of the Patent Statutes, it should e understood that I do not limit my invention thereto, since various modifications thereof will suggest themselves to those skilled in the art without departing from the spirit of m invention, the scope of which is set fort 1 in the annexed claims.

What I claim as new and desire to secure by Letters Patent of the United States, is,

1. The process of coating an attenuated metallic article with another metal which consists in heating a quantity of said metal to form a molten bath thereof, passing the article through the molten bath, and applying additional heat to the surface of the bath at the point where the article emerges to prevent the formation of deposits of dross on said article.

2. The process of coating a .wire with another metal which consists in heating a quantity of said metal to form a molten bath thereof, passin the wire through the molten bath, and app ying additional heat to the surface of the bath at the point where the wire emerges to prevent-the formation of deposits of dross onsaid wire.

3. The process of coating a wire with another metal which consists in heating a quantity of said metal to'form a molten bath thereof, passing the wire through the bath, and directing a gas flame onto the surface of said both at the point where the wire emerges therefrom to prevent the formation of deposits of dross on the wire.

4. The process of treating a wire to render it inoxidizable at high temperatures which consists in passing the wire through a bath of molten aluminum while heating the surface of the bath at the point where the wire emerges therefrom to prevent the formation of deposits of dross on the wire.

5. The process of applying a coating of aluminum to a wire which consists in passing the wire continuousl through a path of molten aluminum while irecting a gas flame on said bath at the point where thewire emerges therefrom to prevent the accumulation of deposits of dross on said wire.

6. The process of applying a coating of aluminum to a wire which consists in applying a coating of an intermediate alloying metal, and then passing the wire through a bath of molten aluminum while applying a source of heat to said bath at the point of emergence of the wire therefrom to prevent the formation of deposits of dross on the wire.

7. The process of treating an iron wire to render it inoxidizable at high temperatures which consists in applying a coating of tin to said wire, and then passing the tinned wire through a bath of molten aluminum while heating the surface of the molten aluminum at the point where the wire emerges therefrom to prevent the formation of deposits of dress on the wire. 0

8. The process of treating an iron wire to render it inoxidizable at high temperatures which consists in ap lying a coating of tin to said wire, and t en passing the tinned wire through a bath of molten aluminum while directing a gas flame on the surface of said bath at the point where the wire emerges therefrom' to prevent the formation of deposits of dress on the wire.

9. Apparatus for applying a coating of metal to an attenuated metallic article comprising a crucible, a quantity of said metal in said crucible, means for heating said metal to form a molten bath, means for passing the article to be coated through said bath, and means for heatmg the surface of said bath at the point of emergence of said article.

10. Apparatus for applying a coating of aluminum to a wire comprismg a crucible containing a bath of molten aluminum, means for passing the wire downward into said bath and then upward out of said bath,

Ill

end means for heating the surface of said a bafile cooperating with said wire as it bath at the point where the wire emerges moves upward to set up a circulation of the w there-from molten aluminum in said but and means 11. Apparatus for applying a coating of for heating the surface of said bath at the aluminum to a wire comprising a crucible point where the wire emerges therefrom. containing a bath 0f molten aluminum, In witness whereof, I have hereunto sei; means for passing the wire downward into my hand this 31st day of December, 19%. said bath and then upward out of said bath, GOQDWIN H. HOWE. 

